The present invention relates to an hydraulic driving device for an electric pressurized-gas switch, of which the piston-cylinder systems can each be acted upon by a hydropneumatic pressure accumulator (pressurizer) having a hydraulic pump which feeds several pressure accumulators and is controlled by pressure monitors, and having a gas-monitoring device for the pressure accumulators.
In such a known hydraulic driving device, for instance, a Siemens circuit breaker 3AS2, 362 kV, the gas monitoring is accomplished directly, i.e., the position of a piston movable in the pressure accumulator is determined, for instance, by mechanical means and is evaluated. Direct gas monitoring requires these mechanical means in multiple, according to the number of pressure accumulators used. The mechanical means make possible the generation, specific as to the pressure accumulator, of one or more gas loss signals.
In known hydraulic driving devices, such gas loss signals specific as to the pressure accumulator, for instance, of a Siemens circuit breaker 3AS2, 150 to 300 kV, are generated through the use of indirect gas monitoring.
The gas content of a pressure accumulator is determined here indirectly via the pressure of the hydraulic liquid if the piston has reached a given stop position. This position can be fixed by a stop so that the hydraulic pump works against a quasi-incompressible medium after this position is reached. Thereby, the hydraulic pressure increases steeply and leads to the delivery of the signal of a pressure monitor which is associated with the pressure accumulator.
If one hydraulic pump feeds several pressure accumulators and, for instance, a gas loss occurs in one of the pressure accumulators, the steep pressure buildup is distributed in this pressure accumulator directly to all pressure accumulators fed by the hydraulic pump, so that an occurring correlation specific as to the pressure accumulator occurring or a gas-loss signal is not possible. For this reason, indirect gas monitoring is used in the known systems if one hydraulic pump is provided for each pressure accumulator.